In the gas turbine engine field, compressor and turbine rotors consist of a number of axially spaced rotors each having a plurality of radially extending blades and each alternating with rows of radially extending stator vanes. The working medium gases in the engine flow alternately through rows of rotor blades and rows to stator blades. Each rotor blade has a lower portion or root which is inserted axially into a similarly shaped opening or notch in the periphery of the rotor. Typically, the upstream surface of a rotor blade has a flange for engagement with the rotor periphery limiting axial movement of the blade in a downstream direction and a split ring or sideplate retainer is employed to limit axial movement of the blade in an upstream direction, thus locking the blade in position.
Among the problems experienced with various rotor blade retention constructions and designs is the requirement to remove more than one blade if it becomes necessary to replace a blade. Further, it has been difficult to seal the interface between the blade root and the rotor and minimize gas leakage from the higher pressure downstream side of a compressor rotor to the lower pressure upstream side of the rotor.
It is known to use a split ring to position and retain the rotor blades in position on the rotor. The ring is typically positioned in an annular groove in the periphery of the rotor and in the blade roots, and has a loading slot for installation of the blades. Another retention system which has been employed invokes the use of side plates or segments which sometimes are affixed to the rotor. In addition, to the systems used to retain and seal the blades installed on a rotor, damping of vibratory stresses sometimes is achieved by the use of damper weights in spaces between the blade roots and the rotor.
One of the problems with known systems is that removal and replacement of a single blade or weight sometimes requires that more than one blade be removed to replace a single blade or weight. Another problem is that shrouded blades cannot be used in systems which employ a loading slot.
U.S. Pat. No. 4,730,983 discloses a rotor blade locking and sealing system using two split rings, but the system requires a loading slot and cannot be used for shrouded blade designs. U.S. Pat. No. 3,888,601 uses a snap ring to retain rotor blades, and U.S. Pat. No. 4,566,857 employs circumferentially extending scalloped pins to lock and seal rotor blades.
Because of the importance of simplicity of maintenance and assembly of jet engines as well as the minimization of pressure losses, improvements in jet engine construction are constantly being sought.